  .content {
      width: 9rem;
      height: 4.5rem;
      margin: 2rem auto;
      overflow: hidden;
      position: relative;
  }
  
  .box {
      width: 100%;
      height: 100%;
  }
  
  .box ul {
      width: 100%;
      height: 100%;
  }
  
  .box ul li {
      float: left;
      position: absolute;
      top: 0;
      left: 0;
  }
  
  img {
      width: 100%;
      background: rgba(255, 255, 255, .8)
  }
  
  .box1 ul {
      width: 100%;
      margin: 0 auto;
      height: 100%;
      border-radius: 15px;
  }
  
  .box ul li {
      opacity: 0;
  }
  
  .box ul li.block {
      animation: play 2s forwards;
  }
  
  .box ul li.b {
      opacity: 1;
  }
  
  @keyframes play {
      0% {
          opacity: 0;
      }
      100% {
          opacity: 1;
      }
  }